It has been known to prepare pyrryl-2-acetonitriles, for example, pyrryl-2-acetonitrile and N-methylpyrryl-2-acetonitrile, by reacting trimethyl-(pyrryl-2-methyl)-ammonium-iodide or trimethyl-(N-methylpyrryl-2-methyl)-ammonium-iodide, respectively, with sodium cyanide. Trimethyl-(pyrryl-2-methyl)-ammonium-iodide and trimethyl-(N-methylpyrryl-2-methyl)-ammonium-iodide are formed in known manner by adding methyl iodide to an alcoholic solution of dimethyl-(pyrryl-2-methyl)-amine or dimethyl-(N-methylpyrryl-2-methyl)-amine, respectively, see J. Amer. Chem. Soc. 73, 4921 (1951) and J. Amer. Chem. Soc. 75, 483 (1953).
The above mentioned processes have particularly the disadvantage that the ammonium salts prepared from the Mannich bases by reaction with alkyl iodides in absolute alcohol must be isolated prior to their further reaction to the corresponding nitriles. Furthermore, the isolated ammonium compounds decompose easily, whereby the yield of pyrrylacetonitriles is adversely affected.
To overcome the above difficulties, Orth et al. in U.S. Pat. No. 3,523,952 conducted the displacement in a water-immiscible solvent. On the scale disclosed in the examples, the procedure of Orth et al apparently is satisfactory since the addition of the alkali cyanide to the quaternary salt at room temperature does not produce reaction. However, upon heating the reaction mixture to 80.degree. C., the reaction starts and is completed by maintaining the temperature for two hours. Since the reaction is exothermic, such procedures are not practical for large scale operations because the exotherm causes severe evolution of gas, foaming and is difficultly controlled upon heating the entire reaction mass. The process of the present invention has been found to overcome these disadvantages. There is provided an extremely efficacious and practical process for the production of pyrryl-2-acetonitriles.